Glycine max-Rhizobium interaction is a well known symbiotic association occurring in nature and responsible for biological nitrogen fixation. Thiram a well-known fungicide has been in practice as seed dressing in order to prevent fungal colonization. In the present study the effect of various thiram concentrations is investigated. Thiram concentration beyond 500 g/ml was observed to be highly toxic with respect to plant growth factors and rhizobial infection to the G. max. The nodulation, nodule dry weight, nitrogenase activity were observed to be maximum at 100 g/ml of thiram. The study is useful in determining the threshold concentration of fungicide for soybean seed dressing for effective nitrogen fixation and crop yield.

Madhya Pradesh is the major soybean contributor in India. The taxonomy of nitrogen fixing bacteria forming symbiotic associations with leguminous plants has been deeply changed in recent years. The use of very sensitive and accurate molecular methods has enabled the detection of large rhizobial diversity. Molecular biotyping and characterization the Bradyrhizobium, isolates from eleven varieties of soybean from agricultural field of Sehore district of Madhya Pradesh is done using 16S rDNA typing. Bradyrhizobia were identified genetically by determining the %Guanine plus Cytosine content of the whole genome, followed by 16S rDNA-RFLP analysis % Guanine plus Cytosine content of all the Bradyrhizobium isolates reflects similarity at generic level among all Bradyrhizobial isolates. Restriction Fragment Length Polymorphism (RFLP) further showed a considerable level of genetic diversity among the Bradyrhizobial isolates. PCR-RFLP of 16S rDNA supported existence of two divergent groups among indigenous Bradyrhizobial isolates, at similarity level of 66, and 75 and 74% of similarity within the group. The technique used was helpful in characterizing Bradyrhizobium isolates to be used as inoculants for improving productivity of agricultural land of Madhya Pradesh (India).

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<p>The microbial biomass of soil is defined as the part of the organic matter in the soil that constitutes living organisms smaller than the 5-10 mm^3.It is generally expressed in the milligrams of carbon per kilogram of soil or micrograms of carbons per gram of dry weight of soil. Typical biomass carbon ranges from 1 to 5% of soil organic matter. Biomass literally means “mass of living material” and can be expressed in units of weight (grams) or units of energy (calories or joules). Biomass is an important ecological parameter as it represents the quantity of energy being stored in a particular segment of biological community.             </p>               Measurement of biomass is used to determine standing crop of a population and transfer of energy between trophic levels within an ecosystem. A measure of the total microbial biomass in soil is often required when studying productivity or fertility of soils. Sometimes the biomass of specific parts of the microbiota is required-for example fungal biomass versus bacterial biomass.